allison transmission

[clarice]

Hi everybody,

I am getting ready to buy my first truck - a Kenworth T300 straight truck, and I don't know too much about the Allison transmission (that I am considering getting if you guys think it's worth it). Does anybody know if they are reliable or not? Any positive or negative experiences? I would really appreciate your input or advice; I need to make a decision soon.
Thanks!
Clarice

 

[davekc]

They are pretty much bullet proof. Should come with a 500,000 mile warranty. Keep in mind they do add weight and cost, but I personally think they are worth every penny.

 

[arkjarhead]

They put those trannys in the battle tanks so they must be pretty good right. I know it's not the same exact tranny as what's in the trucks, but it is the same company.

 

[piper1]

Make sure you only use an Allison approved synthetic fluid (Transynd from Allison or the Fleetrite from an IH dealer) and change the filters on the transmission at the recommended intervals.

If you give it this love it will love you back!!

 

[ATeam]

Our experience with an Allison transmission was negative, from a fuel economy standpoint. If you are considering a standard transmission and not the automatic (auto-shift, or whatever the proper name is for it...two pedals on the floor), this may not apply.

When driving fleet owner trucks, we once drove a Freightliner Century Class with a Detroit 500 engine, tandem drive axles and ten-speed Eaton auto-shift. We averaged 9.5 mpg with it. Later, we moved into a similarly spec'ed Freightliner Century Class truck, only with an Allison six speed transmission. We averaged 6.5 mpg in that one.

Though, we have never before or since driven a truck that was as quick off a red light as that one. But we prefer fuel economy to low-end speed and were glad to get out of that truck.

I don't know what kind of latitude you may have, if any, in spec'ing an automatic transmission. I believe this model was designed more for in-city vehciles like garbage trucks and city buses. It was not a good choice for an expediter truck that sees mostly highway miles.

The transmission itself worked fine but no matter how light we were with the right foot, that truck ran a whole lot of fuel money down the drain.

 

[Moot]

A transmission is only part of the driveline equation. Rear end gear ratio is another factor. Like Phil stated, Allison transmissions are common in city use vehicles. You may be limited to a 4.10 or lower gear ratio in which case your fuel economy would definitely suffer. Check with your dealer to find the highest differential gear ratio that will work with this transmission. Be prepared to go to "plan B".

 

[TeamCaffee]

We have the 6 speed Allison Transmission and average 9.5 m.p.g. we also only drive 59 m.p.h. We have done many things to our truck though to improve our fuel mileage. We have had very good luck with our transmission and for a new person learning to drive a truck you could not ask for an easier transmission to learn on. We have a really good transmission shop in Saint Louis we use that keeps us in good shape.

 

[arkjarhead]

Phil,
You had a 500 hp motor with only six gears behind it? If that's the case that was the problem. I know Allison makes trannys with more gears than just the six. I've seen 9s before I know.

I prefer Eaton trannys hands down. There is another one out there that is alright, but I know I can't spell the name right. Mertior something like that. It's a pretty good tranny in the 10 speed manual version.

 

[EASYTRADER]

I have an Allison 3000RDS in my Hino its an Auto. My only complaint in the maintenance costs. You are supposed to change the fluid and internal filters every 50to70k miles which in an expedite truck will be about three times per year. The cost for this service is anywhere from about 300 to 500 depending on where you get it done.

So right off the bat you have at least $1200.00 a year in scheduled maintenance. The auto shift is nice but had I known that up front I probly would have opted for a standard shift .

 

[piper1]

I have an Allison 3000RDS in my Hino its an Auto. My only complaint in the maintenance costs. You are supposed to change the fluid and internal filters every 50to70k miles which in an expedite truck will be about three times per year. The cost for this service is anywhere from about 300 to 500 depending on where you get it done.

So right off the bat you have at least $1200.00 a year in scheduled maintenance. The auto shift is nice but had I known that up front I probly would have opted for a standard shift .

First off, make sure you have an RDS, Not saying you don't but sometimes an HS (Highway Series) is sold as an RDS which is a Rugged Duty, more akin to on/off road.

Next, go to ,

http://www.allisontransmission.com/servlet/DownloadFile?Dir=publications/pubs&FileToGet=OM3752EN.pdf

Page 61 has the fluid change mileages and it explains what it considers severe service (expedite is not).
This is with synthetic oil and the cheaper filter kit. A fluid drop and filter change on a 3000 series shouldn't take more than an hour and the filters are under 100 bucks. Yes the syn fluid is expensive but it does last a lot longer. Yours needs 17-19 quarts which should cost around 120. That's for the genuine Allison fluid, the Fleetrite stuff is cheaper.

If yours does not have synthetic in it and you want to change it over, I highly recommend you get it done at an Allison Distributor. There will be no issues with warranty and they have the right equipment to flush it, regular flush machines will damage a new style Allison.

If you haven't, talk to an Allison rep or call thier 1-800 number. You may not have to service it as often as you are, Allison assumes RDS's are in dump trucks and the like. Sitting behind a Hino engine and running the highway is an easy ride for that model.

 

[davekc]

I would say Piper has it right. Most of it depends on how the truck is speced and what type of Allison is in it.
I would suspect as in Phil's case it was the wrong Allison transmission, or the rear end ratio was not matched correctly for the application.
If one is only getting 6.5 mpg, it sounds like it is setup for a dump application.

 

[chetjester]

I'm driving an '05 M2 106. 330 hp. I have the 6 speed Allison. It has an overdrive that kicks in at what I think are strange speeds, but, when it does, my mileage goes way up.

It took a while to understand the overdrive, but now I put it in cruise and watch my tach. I can drive 65 mph and be taching 1700. If I tap my cruise and increase the speed to 67, it drops down to 1550 when the overdrive kicks in.

If my personality would allow me to drive under 60 (which I do by law in some states), the tach would be under 1500.

I just have to keep my eye on the dials and I can save money.

The thing to understand is that the Allison is just an automatic transmission. It isn't in any way as efficient as an Eaton auto-shift. The auto-shift has better computer control and works as a direct drive transmission. I just don't know if they are available on our straight trucks.

 

[TeamCaffee]

That is a really good point on watching the tach. If we drive right at 55 mph we get terrible fuel mileage we have to move up to 57 and get the transmission to switch gears and the tach will drop.
When we replace this truck though we will go with a direct drive transmission to get even better fuel mileage.

 

[gojack]

I had a Peterbilt 335 w/an Allison...
I now have a Volvo with a Meritor Freedomline.

The Allison's torque converter will cause a drop in MPG's in the lower gears (in city driving).
if you are primarily in high gear/interstate driving (with the torque converter locked out)
this would have little to no impact on you overall fuel economy.

I would look carefully at an automated transmission, the Kenworth T-300
is available with the Eaton Autoshift Transmission.

The Automated Transmission will be lighter, cheaper, more fuel efficient and less maintenance.

As far as rear-end ratios etc., look at Cummins powerspec website
it walks you through specing very nicely

Cummins PowerSpec


A little additional reading material,

No shifty business - CCJ Magazine
Give Up The Joy Of Shifting? Maybe You Should
Auto Shift To Save Fuel
Autoshift Can Help
Understanding The AutoShift
Eaton Unveils 7-Speed AutoShift
eaton autoshift / ultra shifts - Fleet Maintenance Forums
The two-pedal shift
Allisons Help Drivers And Drivelines - 02/01/2004 - Construction Equipment

 

[clarice]

Thanks everybody!

 

[davekc]

Some good points. Remember also on some Allisons they have a mode button that is set incorrectly. Many don't take the time to read a manual and have it set for city driving, Will make a certain difference of fuel economy.
Also, if the rpm's are too high, take it to the dealer and have the computer perameters changed. They will do it if it falls in the range of the manufacturers specs so the warranty isn't voided.

 

[Dynamite 1]

like stated, allisons are bullet proof if taken care of. you may want to check your service intervals with allison dealers {detroit/allison-clark power service} any allison branded service center. we have an allison in our m2/112, it is the hs4000 series. it requires service every 75,000 mi., however only a filter change is required the second 75,000 if you use the transynd synthetic fluid. as far as fuel mileage goes we are at a steady 9.0 to as high as 10.2 depending on all of the factors that play against fuel economy and there are many, but we are always at 9.0 or better. the specs on the trk. so you all know for comparison. 2005 m2/112, 410hp 4000 series mbe/1450torque, 3.73 rear end/.0017 final drive in 6th on the tranny{i believe}, single rear axle, fullyloaded w/fuel and water and all our stuff and us the trk is a hefty 23,400#. the trk set up as it is turns 1385 rpm@70mph in 6th at 55mph in 5th gear 1250rpm at 61 where it shifts into 6th the rpm is rite @ 1200. so as you can see decent/good fuel mileage is possible with a automatic but as stated you must spec, spec, spec. we can not stress this enough. just a quick example, a friend has the exact same trk. only difference is he weighs 600# less and has 3.91 gears but his fuel economy is 8.5 to 9.5 every little change makes a difference. so if not ordering a trk and buying a dealer stock trk do your homework and check all the specs not just a few. have the final drive spec recalculated by someone other than the dealer who knows something about doing so. find the sweet spot for good economy and decent performance/pulling power. hope all this is helpful as well as understandable. good luck and willbe glad to help if we can. TNT